Why are bonds important?

They can tell a lot about the economy

http://www.cmegroup.com/trading/interest-rates/us-treasury/10-year-us-treasury-note.html

http://www.cmegroup.com/trading/interest-rates/us-treasury/30-year-us-treasury-bond.html

2 TImes 10 year Note - 30 Year Bond 

Strong Economies - /ZB price is less than /ZN Price (long term yield is more than short term)

Weak Economies - /ZB price is more than /ZN Price (long term yield is less than short term )